/**
 * @description 随机验证码
 */
import React, { useEffect, useState } from 'react';

interface VerificationProps {
  /* 随机验证码的数量 */
  length?: number;
  /* 验证码的样式 */
  style?: {
    /* 随机点 */
    dot: boolean;
    /* 随机线 */
    line: boolean;
    width: number;
    height: number;
  };
}
class Verification {
  code: null | string;
  path: null | string;
  length: number;
  width: number;
  height: number;
  dot: boolean;
  line: boolean;

  constructor(
    length = 6,
    style = {
      width: 300,
      height: 50,
      dot: true,
      line: true,
    }
  ) {
    this.code = null;
    this.path = null;
    this.length = length;
    this.width = style.width;
    this.height = style.height;
    this.dot = style.dot;
    this.line = style.line;
  }

  createChars() {
    // 创建随机字符串
    const chars =
      'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    const maxLength = chars.length;
    let code = '';
    for (let i = 0; i < this.length; i++) {
      code = code + chars.charAt(Math.floor(Math.random() * maxLength));
    }
    this.code = code;
    this.createPath();
  }

  // 构建canvas
  createPath() {
    const randomNum = (min: number, max: number) => {
      return Math.floor(Math.random() * (max - min) + min);
    };

    // 随机生成字体颜色
    const randomColor = (min: number, max: number) => {
      const r = randomNum(min, max);
      const g = randomNum(min, max);
      const b = randomNum(min, max);
      return 'rgb(' + r + ',' + g + ',' + b + ')';
    };

    const canvas = document.createElement('canvas');
    canvas.width = this.width;
    canvas.height = this.height;
    const ctx = canvas.getContext('2d');

    if (ctx) {
      ctx.textBaseline = 'middle';
      ctx.fillStyle = randomColor(180, 240);
      ctx.fillRect(0, 0, this.width, this.height);

      for (let i = 0; i <= this.length; i++) {
        const chart = this.code ? this.code[i] : '';
        const x = (this.width / this.length) * i;
        const y = this.height / 2;
        const deg = randomNum(-10, 10);

        ctx.font = randomNum(this.height / 2, this.height) + 'px SimHei';
        ctx.fillStyle = randomColor(50, 160);
        ctx.shadowOffsetX = randomNum(-3, 3);
        ctx.shadowOffsetY = randomNum(-3, 3);
        ctx.shadowBlur = randomNum(-3, 3);
        ctx.shadowColor = 'rgba(0, 0, 0, 0.3)';
        ctx.translate(x, y);
        ctx.rotate((deg * Math.PI) / 180);
        ctx.fillText(chart, 0, 0);
        ctx.rotate((-deg * Math.PI) / 180);
        ctx.translate(-x, -y);
      }

      // 绘画随机线条
      if (this.line) {
        for (let i = 0; i < this.length; i++) {
          ctx.strokeStyle = randomColor(40, 180);
          ctx.beginPath();
          ctx.moveTo(randomNum(0, this.width), randomNum(0, this.height));
          ctx.lineTo(randomNum(0, this.width), randomNum(0, this.height));
          ctx.stroke();
        }
      }

      // 绘画随机点
      if (this.dot) {
        for (let i = 0; i < this.width / this.length; i++) {
          ctx.fillStyle = randomColor(0, 255);
          ctx.beginPath();
          ctx.arc(
            randomNum(0, this.width),
            randomNum(0, this.height),
            1,
            0,
            2 * Math.PI
          );
          ctx.fill();
        }
      }
    }

    this.path = canvas.toDataURL('image/png');
  }

  // 验证输入的验证码是否与生成的相等
  verifyEqual(code: string) {
    return code.toUpperCase() === this.code!.toUpperCase();
  }
}

const VerificationImage: React.FC<VerificationProps> = (props) => {
  const { length, style } = props;
  const [url, setUrl] = useState('');

  useEffect(() => {
    const v = new Verification(length, style);
    v.createChars();
    setUrl(v.path as string);
  }, []);

  return (
    <img
      src={url}
      alt=""
    />
  );
};

export default VerificationImage;
